1. Field of the Invention
The present invention generally relates to tools, and more specifically to a driver tool and attachment which embodies a high energy permanent magnet magnetizer and a selective demagnetizer for selectively magnetizing and/or demagnetizing a magnetizable element, such as a driver bit, fastener, and the like.
2. Description of the Prior Art
It is frequently desirable to magnetize the tips of screwdriver bits, tweezers and the like to form at a least temporary magnetic pole on the tool which attracts magnetizable elements. Thus, particularly with precision screwdrivers which tend to be relatively small and are used to drive relatively small screws, it is frequently advantageous to at least temporarily magnetize the screwdriver tips of the driver bits to maintain the screwdriver tip blade within the slot of a head of a screw or a Phillips driver within the cross slots formed within the head of the screw adapted to receive the Phillips screwdriver tip. By magnetizing the tip of the driver bit, and mating the tip within the associated opening in the head of the screw, the screw remains attached to the bit tip without the need to physically hold them together. This allows the screw to be guided through a relatively small bore or channel and moved within confined spaces. Sometimes the magnetized tip of the driver bit is used to retrieve a metal item, such as a screw, washer, nail or the like, from an inaccessible place which would otherwise be difficult to reach with anything but a relatively thin shank of a bit driver. Of course, such attachment of a fastener to the driver bit tip also frees one hand for holding or positioning the work into which the fastener is to be driven. In some instances, rather than magnetizing the tip of the driver member bit, the fastener itself is magnetized so that, again, it is attracted to and remains magnetically attached to the driver bit tip in the same way as if the latter had been magnetized.
Conversely, there are instances in which a magnetized driver bit tip is a disadvantage, because it undesirably attracts and attaches to itself various magnetizable elements or components. Under such circumstances, it may be desirable to demagnetize a driver bit tip that had been originally magnetized in order to render same magnetically neutral.
Devices for magnetizing/demagnetizing tools and small parts are well known. These normally incorporate one or more permanent magnets which create a sufficiently high magnetic field to magnetize at least a portion of a magnetizable element brought into its field. The body can be magnetized by bringing it into the magnetic field. While the magnetic properties of all materials make them respondent in some way to magnetic fields, most materials are diamagnetic or paramagnetic and show almost no response to magnetic fields. However, a magnetizable element made of a ferromagnetic material readily responds to a magnetic field and becomes, at least temporarily, magnetized when placed in such a magnetic field.
Magnetic materials are classified as soft or hard according to the ease of magnetization. Soft materials are used as devices in which change in the magnetization during operation is desirable, sometimes rapidly, as in AC generators and transformers. Hard materials are used to supply fixed fields either to act alone, as in a magnetic separator, or interact with others, as in loudspeakers, electronic instruments and test equipment.
Most magnetizers/demagnetizers include commercial magnets which are formed of either Alnico or of ceramic materials. The driver members/fasteners, on the other hand, are normally made of soft materials which are readily magnetized but more easily lose their magnetization, such as by being drawn over an iron or steel surface, subjected to a demagnetizing influence such as strong electromagnetic fields or other permanent magnetic fields, severe mechanical shock or extreme temperature variations.
One example of a stand alone magnetizer/demagnetizer is magnetizer/demagnetizer Model No. 40010, made in Germany by Wiha. This unit consists of a plastic box that has two adjacent openings defined by three spaced transverse portions. Magnets are placed within the transverse portions to provide magnetic fields in each of the two openings which are directed in substantially opposing directions. Therefore, when a magnetizable tool bit or any magnetizable component is placed within one of the openings, it becomes magnetized and when placed in the other of the openings, it becomes demagnetized. The demagnetizing window is provided with progressive steps to stepwise decrease the air gap for the demagnetizing field and, therefore, provides different levels of strengths of the demagnetizing field. However, common magnetic materials that are used with conventional magnetizers/demagnetizers include Alnico and ceramic magnets which typically have energy products equal to approximately 4.5.times.10.sup.6 gauss-oersteds and 2.2.times.10.sup.6 gauss-oersteds, respectively.
Since the magnetic field strength "B" at the pole of the magnet is a product of the unit field strength and the area, it follows that the energy content is proportional to the BH product of the magnet. The BH product is a quantity of importance for a permanent magnet and is probably the best single "figure of merit" or criterion for judging the quality of the permanent magnetic material. It is for this reason that conventional magnetizers/demagnetizers have required significant volumes of magnetic material to provide the desired energy content suitable for magnetizing and demagnetizing parts. However, the required volumes have rendered it impossible or impractical to incorporate the magnetizers/demagnetizers on relatively small hand tools. Thus, for example, precision screwdrivers, which are relatively small and have relatively small diameter handles, could not possibly incorporate sufficient magnetic material to provide desired levels of magnetic fields for magnetizing and demagnetizing parts. However, the requirement of using separate magnetizer/demagnetizer units has rendered their use less practical. Thus, unless the user of a precision screwdriver or any driver tool acquired a separate magnetizer/demagnetizer, one would not normally be available for use. Additionally, even if such magnetizer/demagnetizer were available, it would still require a separate component that could be misplaced and not be available when needed. Additionally, there is always the risk that the magnetizer/demagnetizer could become misplaced or lost, rendering the use of the driver tool less useful.
Another problem with prior art magnetizers/demagnetizers is that they fail to address the problem that during "demagnetization" the element being demagnetized may be either insufficiently demagnetized or overly demagnetized to effectively re-magnetize the element with opposing polarity. Thus, prior art magnetizers/demagnetizers have failed to consider the importance of the strengths of the magnets and the sizes of the elements being magnetized and demagnetized. Thus, typically, the larger the element, the more magnetic field required to demagnetize it. However, demagnetization of all sized elements within the same field may result in some elements being insufficiently demagnetized, while others become overly demagnetized. In either case, the end result is unsatisfactory in that an element which was intended to be demagnetized continues to exhibit magnetic poles and generate a magnetic field.